Installing a pre-hung door in your house may be straightforward and quick, but for optimal results it must be completed in the right way. Your goal should be a door that swings freely and latches properly.
Start by checking the wall framing and trimmer studs with a level and plumb bob to ensure they’re plumb, then use shims to keep jambs flush with the drywall surface.
Shims
Pre-hung doors make installation much simpler, as their hinges and lockset are already attached – this makes this type of door much simpler to put up than its slab counterpart, which requires purchasing, installing and aligning its frame, hinges, latch hardware separately. Still, professional results require using both a level and tape measure; first take steps to ensure trimmer studs are even with wall and trim. If they differ by more than 1/4 inches you’ll need to shim out the opening prior to hanging your new door.
Shim the hinge-side jamb to ensure it’s level using a level or bubble hammer, then adjust its strike side shim accordingly – but be careful not to make too large of adjustments, otherwise your door could hit with an audible bang when opening and closing it! Keep tweaking until the reveal along the top of the door is uniform before applying a bead of caulk around its sill to protect it from water damage caused by rain and other sources.
Caulking
Once your pre-hung door is in place and its shims installed, apply caulking around its molding on all three sides of its new frame to help prevent water from seeping into any gaps between panels and rotting the frame. This step should help reduce moisture leaking into its gaps and causing frame rot.
Before closing your door, always double check that it fits snugly and if there are gaps, add more shims as soon as possible.
Before beginning to shim the lock side of your frame (strike side), be sure to test that your door closes and locks correctly by opening and closing it several times. This will ensure that everything fits smoothly when closing and locking it again.
Next, use a level to ensure the center of your strike side frame is plumb before filling any gaps with wood shims until it’s level. Repeat this process on both sides until all gaps have been filled in levelly and caulk around sill gaps to keep water out.
Trim
Installing doors is one of the most satisfying home improvement projects you can undertake, yet also one of the more challenging. Failure to properly install it could result in it not opening or closing correctly – to prevent these complications, start by gathering supplies and unpacking prehung door units without packing restraints attached to them.
Use a level to ensure the head jamb is flush with both wall and plumb, or add shims until both hinge sides are even with each stud. If any hinge side is lower than any latch side, add them accordingly until all are even.
As soon as the hinge side is level, hammer finish nails through the shims and into the studs using finish nails. Do this on both hinge sides before filling any nail holes with wood putty or filler before sanding any trim edges until smooth. Now it’s time to hang your new door! To help with this task more easily it would be beneficial to enlist help from another person since prehung doors can be heavy and awkward to install alone.
Nails
Once the casing and trim have been installed, use putty to hide nail heads so they will become less visible – this allows for easier painting or staining as desired.
Before installing the new door, ensure it matches the existing one by carefully inspecting its hinge side and dead bolt latch side. If the latch is on the right, this indicates it is right-handed while if on the left it means left-handedness.
Once the door frame has been shimmened, take note of whether or not its head jamb “reveal” is larger or smaller than the gap on its latch side of the frame. If it is, cut a piece of MDF 7.5 inches wide that measures equal to one side piece’s outer edge length and nail that into place to close any discrepancies.
Assemble your trim securely by inserting several 3″ screws through it and the surrounding studs, taking care not to overscrew as this could cause it to detach from its frame over time. Be wary not to drive these in too deeply as that could lead to pullback of trim from its frame over time.